Midrapidity Source of Intermediate-Mass Fragments in Highly Central Collisions of Au+Au at 150 AMeV

Charged particles have been observed in collisions of Au+Au at an incident energy of 150 AMeV using a high-granularity detector system covering approximately the forward hemisphere in the center-of-mass system. Highly central collisions have been studied using a double selection criterion which combines large charged-particle multiplicities with small transverse-momentum directivities. In this class of events about one-quarter of the total nuclear charge emerges as intermediate-mass fragments with nuclear chages Z>2. These fragments are centered at midrapidity and are produced with large transverse velocities.